Engine Stalls

[ccvi]

Originally posted by Kweassa
Failure of throttle systems.. <- this one is in FB.

 Get hit in the wrong place, and your throttle doesn't respond, jammed and stuck. Makes those emergency landings really interesting..

Just close the fuel supply.

edit: This should be done at every emergency landing anyway.

[Ack-Ack]

Originally posted by GScholz
Interesting. How would this affect radial engines, and the DB which was an inverted V?

OK, I asked a resident Big Weeker and former WW2 pilot, Earl, about this and this is what he said about his own experience.  I think by his answer you can come to the conclusion that not many US aircraft had such an oil system to support prolonged inverted flight.  Earl not only flew the P-47 but also had combat experience in the P-38G, P-39N/Q in the MTO so he's speaking from experience in a broad range of aircraft.

The only fighter I know that had a provision for supplying oil to the engine while in continuos inverted flight (although, for the life of me, I don't know why), was the P-47N.  One of the check list items for the maintenance test flights that I conducted was to check the oil pressure while the aircraft was inverted with negative G's. The P-47N had an oil sump that would rotate with regard to G forces.   I would check to make sure the oil pressure came back up to normal after commencing inverted flight.

earl

ack-ack

[GScholz]

Interesting, so the problem would be in the oilpump design and it's corresponding system, not in the engine itself. (Normal engines like those in cars cannot be run inverted because of the oilpan would flood the engine with oil, or so a mechanic friend of mine says. He was allso very sceptical to how the 4-stroke DB could work with inverted cylinders, most radials were 2-stroke so that was ok.)

[Ack-Ack]

From Earl's comments I'd say you're correct.  I do find it strange though that more fighters didn't have an inverted oil system to provide oil while in inverted flight.  You would think it would have been standard because of the nature of the planes and what was required of them.  I know that the P-38 had no such system in place.


ack-ack

[JB73]

you guys shoulda been @ the con... HiTech talked a lot about the inverted oil sump for his plane that he wants

[straffo]

Originally posted by Ack-Ack
From Earl's comments I'd say you're correct.  I do find it strange though that more fighters didn't have an inverted oil system to provide oil while in inverted flight.  You would think it would have been standard because of the nature of the planes and what was required of them.  I know that the P-38 had no such system in place.


ack-ack

Perhaps ,because you don't fly long inverted in combat ?

How long can resist an engine when working inverted ?
If it's (for example) 5 minutes there is no need for a special equipement

[BGBMAW]

scholz...

radial engines are 2 strokes!!!????

[mos]

From what I read, the P-38 will sustain 10 seconds of inverted flight safely.  After that, you're pushing your luck.  I'll try and find the link, but it was awhile ago.  Could be anywhere.  

[SKurj]

Hmm and how many pilots in ww2 wanted to fly extended periods under negative G?

Its not inverted thats the issue.. as much as negative G surely...?


SKurj

[Ack-Ack]

Originally posted by SKurj
Hmm and how many pilots in ww2 wanted to fly extended periods under negative G?

Its not inverted thats the issue.. as much as negative G surely...?


SKurj

This is from the war story of Charles Hoffman.  In this part he's talking about the fly-bys of the "Black Cat" squadron of the 155th Autonomous Fighter Group and how they were able to fly inverted for prolonged periods and why the P-38 couldn't.

A co-occupant of the airdrome was the famous Italian Air Force “Black Cat” squadron of the 155th Autonomous Fighter Group. They were touted to be on par with the German “Yellow-Nose” squadron. The rumor was that only fighter aces could fly with them. Later we found that this was not true, but I will say they were good pilots. Since their Macchi 202s, 205s, and Reggiane 2001s could fly inverted, the Italians would buzz the field in a tight formation with half of the planes inverted. Our planes were limited to a very short time in the inverted position. The P-38 did not have a fuel injection system and the oil system needed gravity to work properly. In the inverted position, the engines quickly became starved for lubrication and fuel. All the Italian planes were exceptional aircraft. We were glad the Germans insisted on flying their own aircraft.

From this guy's comments and from Earl's earlier, it sounds more like flying inverted is the problem rather than pulling negative Gs, as would be the problem with the Spitfire I.

Originally posted by straffo
Perhaps ,because you don't fly long inverted in combat ?

How long can resist an engine when working inverted ?
If it's (for example) 5 minutes there is no need for a special equipement

If the P-38 was unable to fly the length of a field inverted without the engine becoming starved for lubrication or fuel or that when Earl test flew a P-47N, he had to make sure the oil pressure returned to normal after commencing inverted flight.  And that was in a plane that was equipped with an inverted oil system.  So the time probably wasn't all that long before you started seeing problems with the engine.

Ack-Ack

[GScholz]

Originally posted by BGBMAW
scholz...

radial engines are 2 strokes!!!????

I believe most of them were yeah. Ever noticed that blue-grey smoke pouring out of the exhaust as they start up, you don't see that on the V's. The blue-grey smoke would be from the oil they had to mix with the fuel to lubricate the piston-heads. Didn't the B-17 have huge oil tanks in the inner wing section?

[BGBMAW]

wow.....yes they do smoke..and b-17s have veryy large oil reserves...but....

i really thought they had valves...like a 4 stroke...

strange..

BiGB

[icemaw]

Originally posted by BGBMAW
wow.....yes they do smoke..and b-17s have veryy large oil reserves...but....

i really thought they had valves...like a 4 stroke...

strange..

BiGB

 LOL alltho a radial could be a 2 stroke just as any other engine configuration could be a 2 stroke. The b17 radials are not. They are 4 stroke. Engine configuration has little to do with inverted flight and has everthing to do with wether the engine is as DRY SUMP or not. A wet sump engine stores oil in the crankcase when inverted the oil would flow down the oil passages into the valve cover and or lifter valley on V configured engines.  Not to mention all the drag of the oil on the crank rods and pistons. A dry sump engine can run at any angle. The engine in the bf109s are inverted V ie the crank is on the top and the heads are on the bottom it is dry sump.  I wont pretend to know startup procedures of radial engine but it would seem to me part of the cause of blue smoke at startup is from oil film leaking past the rings and pooling in the lower cylinders. I seem to recall that radial must be turned thru several revolutions to clear oil from lower cylinders.

[MrCoffee]

Originally posted by GScholz
I believe most of them were yeah. Ever noticed that blue-grey smoke pouring out of the exhaust as they start up, you don't see that on the V's. The blue-grey smoke would be from the oil they had to mix with the fuel to lubricate the piston-heads. Didn't the B-17 have huge oil tanks in the inner wing section?

gscholz, this is from the oil that deposits in the upside down cylinder heads on radials. They are  4stroke and not 2stroke. Common practice was to hand turn the propeller a few times to clear the pistons of  oil before starting.

 

[hitech]

I can't think of a plane (other than utrlights) ever built with a 2 stroke.

HiTech